Exhaust fan



Jan. 22, 1952 F. J. HOFFMAN EXHAUST FAN 2 SHEETSSHEET 1 Filed Oct. 18,1950

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FREDERICK J. HOFFMAN (It torneg$ Jan. 22, 1952 F. J. HOFFMAN 2,583,374

EXHAUST FAN Filed Oct. 18, 1950 2 SHEETSSHEET 2 FREDERICK J. HOFFMAN (lttornegs Patented Jan. 22, 1952 "Frederick rLflofl'man, Seattle, Wash, assignor to Hydraulic Supply Manufacturing Company,

.Seattle, Wash.

.Annlicationpctober :18, 1950, SeriaI'No. 190.715

41 mm. an. 98-43) 'My invention relates to fan assemblies; and,

more particularly, to an exhaust fan. "My is designed to'prevent fouling of the ianblades, 4"

:motor and the passageway in which thexfan :ls

positioned, and "to provide convenient access to the passageways through which air from an 'en closure is exhausted, for cleaning and maintenancepurposes. A circular main housing is positheappearance of an exhaustfan; "to exhaust air irom a room by a fan without passing the air through the fan blades, motor and fan housing;

: to provide an economically manufacturable Texhaust fan which is easily installed in a room: to minimize maintenance of an exhaust .fan; to provide ready access to the moving parts in an exhaust fan; and to apply the principles of :a

tioned in an opening in an enclosing member of a room .or the "like. A circular fan housing; is,

positioned within the main housing in spaced relationship and contains a fan. The Ian is disposed to direct air from'outside toward the inside of the enclosure. A dome-shaped baiiie is pos'itionedin front of the exhaust of the'fan with its edges extending between said housingsjfin passageway between the fan and'the main housing. This acts in the manner of a Venturi tube and draws air from the enclosure through the passagewaybetween the'baille and the mainhousing and exhausts the same outside of theenclosure. The battle is removable providing convenient access to all passageways through which air from the room passes, for cleaning and the like.

A problem common to exhaust fans is to prevent fouling fan blades, motor and passageway in which the fan is positioned. A relatedproblem is to provide convenient access to the passageways through which room air passes-aim cleaning and the like. Depending upon thetype of activil yzwithin a room, the type of heating used. etc; the air-in the room hasvarious amounts or impurities therein which deposit on exhaust passageways. If the air passes through the fan blades, motor and fan passageway, theseportions are fouled and require cleaning to -inaintain the ian'in proper operating condition. Often there is oil on these portions and this aggravates the fouling. Unless the fan assembly is frequently cleaned, an unsightly appearance is presented; and the fan assembly itself}, when open to view :as in the ordinary exhaust fan, 'isnot attractive.

'Itis an object of my nvention to prevent rouling of the fan assembly-"in an exhaust fan; to provide convenient access to the room air exhaust passageways in an exhaust ran; to improve Venturi tube to exhaust fans to reduce cleaningv maintenance ofmoving and oily parts. I

My .invention will best be understood from the following description, when read with reference to the drawings, in which:

Figure 1 is a side view, partly in section, of a specific embodiment of my exhaust rfan, with a portion of the wall in which the tan is positioned; v

Figure 2 is a view taken on line 2-2 of Figure 1, partly in section;

Figure 3 is a sectional view taken on line 3-3 of Figure 2; and

Figure 4 is a diagrammatic view showing louver operating means for sealing the fan open ing when the same is not in use.

Mainhousing I0 is positioned in an openingin the enclosing member I2 of a room or the like. In the form shown, housing ID is made of two portions of sheet metal, one portion I'B :beingon the room air inlet side and the other portion l8 being on the air outlet side, secured together by screws 20. Portion l6 carries flange 22 which abuts the inner surface of enclosing member 12. Main housing I0 is circular in transverse crosssection.

Fan housing '30 is positioned within main housing l0 and is also of circular transverse crosssection. Housing '30 is secured in place by bolts 32 and nuts 34 and is spaced from main housing by spacers 36.

Fan motor .40 is set within Ian housing 30 on strap 42. Fan blades 44 are, disposed to direct air from outside enclosing member .10 toward the inside of the room. Louver :means 46, shown in dotted lines in Figure 1, may .be used to protect and conceal the fan.

"In Figure 4 a suitable louver operating means is shown, diagrammatically. As motor 40 is energized by "the usual switch a solenoid 4"! is also energized and louver blades :are moved to their open position. It is to be. noted that the upper louver blades 46a andfthe lower louver blades 46-11 are operated through modified linkage having specially positioned attachment points to operate the upper and lower louvers after the showing of Figure 1. This arrangementis decenter of fan blades 44. Rod 58, across inwardly' projecting portion 55, provides means for pulling baille 50 from engagement with detents 54.

Portion l8 of main housing It! is flared outwardly at 60 on the outer side of enclosing member I2. Fan housing 30 is similarly flared at 62. Ex-

cept for flare 62, the outer surface of fan housing 30 is convexly curved longitudinally. The inner surface of fan housing 30 is concavedly curved longitudinally. Flare 62 and the outside portion ofthe inner surface of fan housing 3ll are formed by bending fan housing 30 and doubling it back on itself, as-at 64. The doubled portion is secured as by screws 66. The purpose of the outward flare of main housing 10 at 60, the outward flare of fan housing 30 at 62 and the doubled portion of fan housing 36, is to prevent intermingling of air passing out at 68 between housin It! and housing v3|] with air entering fan housing 39 at 10.

As the fan directs air against baflle 50, the air is curved to pass through a restricted passageway at 80 .between fan housing 30 and baffle 50. Then the air passes into an enlarged passageway at 82 in the unobstructed areas between fan housing 30 and main housing In. This expansion from a restricted to a larger passageway acts in the manner of a Venturi tube and air is drawn from the room through thepassageway at 84 between bafile 50 and main housing It! and into the enlarged passageway at 82 and out through the flared opening at 68.

Aswill be observed, air from the room does not pass inside of fan housing 30, but passes between main housing l0 and fan housing 30. This passageway is not oily and is formed to collect a minimum of deposits from the room air. Removal of bafile 50 provides ready access to the room air passageway for cleaning. Removal of the bafile also affords ready access to the fan for maintenance of the same, and any deposits irom the outer air collecting inside fan housing 30 or on bafile 50 may be removed. When baffle 50 is in place, the exhaust fan assembly presents a pleasing appearance from inside the room as only baiile 50 and portion 16 of main housing H] are visible.

Although I have shown a specific embodiment of my exhaust fan, I wish to be understood as not limiting myself to the depicted device but wish to claim all devices fairly within the scope of my invention.

'"I claim: r

1. An exhaust fan for exhausting air through an enclosing member of a roomor the like, comprising: a main housing to be positioned in said enclosing member having an air ingress opening at one side and an air egress opening at the other side of said enclosing member, said main housing being circular in transverse cross-section and being flared outwardly at said air egress opening;

:an open-ended fan housing positioned within said main housing, said fanhousing being-circular in transverse cross-section and being spaced from said main housing providing an annular exhaust air passageway between said housing, the

4 inner surface of said fan housing being concavely curved longitudinally and the outer surface of said fan housing being convexly curved longitudinally except that it is flared outwardly opposite the outward flare of said main housing; a dome-shaped baflie removably positioned at the air ingress side of said main housing with its concave faceinward, theedge of said bafiie being positioned'between said main housing and said fan housing in spaced relationship, the width of the space between said edge of said baflie and said fan housing being less than the width of the adjacent portion of said annular exhaust air v passageway; a fan positioned in said fan housing housing, air passing-from said baffle into said annular exhaust air passageway toward said air egressbpening drawing air through said air ingress opening of said inain housing; and said bafile having. a central inwardly projecting por tion directed toward the center of said fan-.-

2. An exhaust fan for exhausting air through an enclosin member of a room or the like, comprising: .a main housing to be positioned in said enclosing member having an air ingress open ing at one side and an air egress opening. at the other side of said enclosingmember, said main housing being annular in transverse cross-section; an open-ended fan housing positioned within said main housing, said fan housing being annular in transverse cross-section and bein spaced from said main housing providing an annular exhaust air passageway between said housings; a bafiie positioned at the air ingress side of said main housing with the edges thereof being positioned between said mainhousing and said fan housing in spaced relationship, the width ,of the space between said edge of .said bafile and said fan housing being less than .the width of the adjacent portion of said annular exhaust air pasageway, the central portion of said baffle being protuberant outward; a fan positioned insaid 'fan housing and disposed to direct air against said baffle and to draw air from the opposite end of said fan housing, air passing from said baflle into said annular exhaust air passageway toward said air agress opening draw,- ing air through said air ingress opening of said main housing.

3. An exhaust fan for exhausting air through an enclosing member of a room or the like, comprising: a main housing to be positioned in said enclosing member having an air ingress opening at one side and an air egress opening at theother side of said enclosing member; an open ended fan housing positioned within said main housing and spaced therefrom providing an exhaust air passageway between said. housings; a .fan positioned in said fan housing; a bafiie positioned at the air ingress side of said main housing, said fan being disposed to direct air against said baflle and to draw air from the opposite end of said fan housing, said baflie being formed to. direct air strikingsaid bafiie into said exhaust air passageway in a direction toward said air egress opening of said enclosing member, and said bafile being disposed so that air passing through said fan and against said baffle passes from a restricted space between said bailie and said fan housing into the larger space of said exhaust air pasageway thereby drawing air through said air ingress opening of said main housing.

.4. An exhaust fan for exhausting air through v an enclosing member of an enclosure. comprising: a fan assembly to be positioned in an opening in said enclosing member, having a fan disposed to drawoutside air from without said enclosing member and direct said outside air toward the inside of said enclosing member; having a baflie positioned on the exhaust side of said fan and formed to reverse the flow of said outside air to direct it toward the outside of said enclosing member; having means forming a restricted passageway for said outside air after its flow has been reversed by said baffle;

having means forming a larger passageway, con-- necting with said restricted passageway, leading to the outside of said enclosing member, whereby air passing through said restricted passageway has room to expand in said larger passageway; and having means forming an air passageway leading from the inside of said enclosing member and connecting with said large passageway near its junction with said restricted passageway, whereby air passing from said restricted passageway will draw air from inside said enclosing member.

FREDERICK J. HOFFMAN.

REFERENCES CITED The following references, are of record in the file of this patent:

UNITED STATES PATENTS 

